During the course of a physical examination on adult males, it is common to perform a rectal examination and palpate the prostate gland. In its healthy state, the prostate gland feels soft and spongy. In cases of possible neoplasm, the gland may feel hard and present as a nodule. Whenever a hard nodule is detected, it must be biopsied in order to obtain tissue for pathologic confirmation of the diagnosis.
Prostatic biopsies have been performed by inserting a needle into the gland to sample tissue. The examiner may use a large #14 gauge biopsy needle to obtain a core of tissue (1.times.3 mm) which is processed for histologic interpretation, or he may use a thin #22 gauge needle to obtain exfoliated cells by aspiration for cytologic interpretation.
If the larger #14 gauge needle is used, ample tissue is generally obtained, but there is a greater risk of bleeding and sepsis because of the relatively large puncture site. Often, repeat biopsies may be required when the core sample is negative for cancer. These repeat biopsies increase the risk of possible complications.
In contrast, if the thin #22 gauge needles are used, then the likelihood of bleeding and sepsis are significantly reduced. The puncture site is small and these needles produce minimal tissue trauma. The prostatic epithelium may be exfoliated from a diffused fan-shaped area in and around the nodule as the needle is withdrawn and reinserted into the gland several times. Recent literature (J. Urology, Vol. 113:955, 1986), suggests that these aspiration techniques increase accuracy over the single core biopsy, and may reduce the risk of complications.
These biopsies may be performed either by the transperineal or transrectal route. However, in order to accurately position the needle through the perineum, expensive ultrasound equipment may be required. In contrast, accurate transrectal placement may be accomplished by means of a simple finger guide. Presently, the transrectal prostatic aspiration biopsy with a finger guide has been widely accepted in clinical practice (J. Urology, Vol. 135:294, 1986). These procedures may be performed inexpensively, in an office setting, even without local anesthesia.
In an attempt to facilitate a low cost and reliable transrectal prostatic aspiration biopsy, I have invented a new disposable flexible needle guide. In the following paragraphs, the prior art will be discussed and the new invention will be compared to these older devices.
U.S. Pat. No. 3,595,217 describes a needle aspiration guide. The '217 patent discloses a needle guide comprising a tubular member or channel having a ring member secured to one end and a stabilizing disk slidably mounted along the length of the channel. In use, one end of the guide is fixed to the operator's gloved index finger by the ring. The disk, positioned in the palm of the operator, facilitates handling of the guide and maintains stability of the channel. The index finger is inserted into the rectum of the patient, and the prostate is palpated. When a suspicious nodule is palpated, a needle is passed through the tubular member in order to puncture and aspirate the suspicious area.
Although this needle guide is durable, it has a number of disadvantages. First, it must be sterilized between cases, which may take time and risks cross-contamination between patients. Additionally, the ring member, attached to the finger of the examiner, may be uncomfortable to the patient as it passes through the anal sphincter. Furthermore, the ring member may also be uncomfortable to the examiner when placed over the tip of the index finger. Also, the hard construction of the ring can interfere with palpation which may make accurate diagnosis difficult.
In the medical publication, "The Lancet," Sept. 1, 1984, page 495, a needle guide is described for use with a #14 gauge needle. This guide comprises a generally flexible collar or ring mounted on the carrier portion through which a gloved index finger may be inserted. Mounted on the base of the carrier portion is a flexible sheath through which a needle may be inserted. Disposed between the flexible sheath and the carrier portion is a stiffener to facilitate insertion of the needle. In use, the finger is inserted into the collar portion so that the volar aspect of the finger is in contact with the carrier. The finger and carrier are then inserted into the rectum of the patient, and the prostate gland or nodule is palpated in the usual manner.
While this needle guide offers some improvements over the one disclosed in the '217 patent, it also has a number of disadvantages. The guide is designed for a large size #14 gauge needle. Furthermore, the carrier portion supporting the flexible sheath, stiffener, and collar may be uncomfortable to the patent as it passes through the anal sphincter. Furthermore, the stiffener placed between the flexible sheath and the carrier portion may make accurate palpation difficult. Still further, this needle guide does not provide adequate stabilization because the collar surrounds only a small circumference of the index finger (around the second joint). Also, since this device is worn over the tip of the index finger, it may inhibit natural movement of the finger as digital examination is being performed. Although this guide is intended to be disposable, it still embodies all of the disadvantages mentioned above.